Concentration Of Dye Solution Research Articles

Capillary-driven flow combined with electric field and Fenton reaction to remove ionic dyes from water or concentrated NaCl solution: Mechanism and application

A strategy to integrate capillary flow, electric field and Fenton reaction was developed to remove ionic dyes from water or concentrated NaCl solution for the first time. Tissue paper was used to construct capillary flow. The flow rates of water and crystal violet (CV) through it were measured, and then fitted with Lucas-Washburn model, Bosanquet model, and the fixed-bed adsorption model, respectively. Subsequently, an external electric field along the paper channels was introduced to prevent CV from flowing through the paper by electrostatic repulsion. Meanwhile, energy consumption of the integrated process was very low. For a concentrated NaCl (above 1 wt%) and dye solution, HClO formed by the electrolysis of Cl- ions further degraded CV. The relationship between voltage and NaCl concentration in the separation process was also investigated. Moreover, Fenton reaction was introduced to regenerate MnO2-coated paper and to enable the reutilization of the polluted device. Finally, removal of three ionic dyes (CV, methyl blue, and methylene blue) in water or 5 wt% NaCl solution were tested with a large paper device, in which the permeate was automatically collected by gravity. All the experiments showed 100% dye rejection with a water flow rate of 10–18 mL/h (at a cross-section area of 25 × 10−6 m2) and an energy consumption of 0.5–0.8 kwhm−3 to treat 100 ppm dye solution, and flow rate of 9–11 mL/h, energy consumption of 4.8–5.2 kwhm−3 to treat a solution of 100 ppm dye and 5 wt% NaCl. Overall, the results demonstrate the significant potentials of this new strategy for dye removal application.

Two-stage adsorber optimization of NaOH-prewashed oil palm empty fruit bunch activated carbon for methylene blue removal

Abstract The objective of the present work was to evaluate the performance of two-stage adsorber of activated carbon from oil palm empty fruit bunch for methylene blue removal. The model was developed to predict optimum adsorbent mass and time at a specified volumes and concentrations of dye solution. Results show that the adsorbent mass can be reduced by 6.67%. Operating time taken to attain the equilibrium in a two-stage adsorber has dramatically decreased from 22 h to 0.52 h. In the performance evaluation, the adsorbent mass in stage-1 is higher than in stage-2, which lessen the workload to achieve equilibrium. A two-stage adsorber aids to optimize the mass and contact time for different percentage of dye removal that economically feasible for industrial applications.

Biodegradation of the Azo Dye Airedale Yellow CHD: Understanding using residuals

Textile industries are heavy users of water and also produce lots of contaminated effluents. The main contaminants are azo dyes. Hence, the effluents are to be treated before leaving in the environment. In this study, the azo dye Airedale Yellow CHD was biodegraded using two bacteria Thalassospira frigidphilosprofundus (NCIM no 5438) and Erwinia chrysanthemi Burkholder (NCIM no 5213) in shaking conical flasks. Effect of Various parameters like pH, temperature, agitation, and concentration of dye solution on its decolorization was investigated. The biodegradation was statistically worked out using MINITAB software for the ANOVA. The residual plots along with the scatter plots for the decolorization of Airedale Yellow CHD using T. frigidphilosprofundus and E. chrysanthemi Burkholder are also obtained and included in this work. The maximum percent removal of the azo dye was obtained by using T. frigidphilosprofundus (77.41%) whereas it was reported at 74.64% by using E. chrysanthemi Burkholder. The obtained results formed a good fit according to the obtained normal residual plot which can conclude that the findings of the study are accurate and satisfactory.

Anisotropic behavior of random lasing in a highly concentrated dye solution.

Angular dependence of the diffusive random laser (DRL) emission is assessed due to excitation of a highly concentrated solution of Rhodamine 6G (Rd6G) comprising monomers and dimers. Dimerization at extremely high concentrations leads to the random fluctuation of the dielectric constant in gain medium. As a result, aggregated dye molecules provide multiple scattering events for propagating photons which is confirmed by enhanced backscattering (EBS) test. This scattering feedback besides Försteŕs resonance energy transfer (FRET) from monomers to dimers provide RL spikes over low quantum yield dimeric fluorescence spectra. The unique spectral feature of RL emission is strong dependence on the angle of detection that results from anisotropic inner filter effect (IFE) within the gain volume due to local excitation of the medium by a pencil-like beam of laser. The results have a merit of importance in optical characterization of the media in which the fluorophores can aggregate significantly.

Green mediated combustion synthesis of copper zinc oxide using Eryngium planum leaf extract as a natural green fuel: Excellent adsorption capacity towards Congo red dye

In the present study, meso/microporous CuO/ZnO nanostructures were synthesized via a green mediated solution combustion method by Eryngium planum leaf extract as natural fuel for the first time. Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectrometer (FTIR), Thermogravimetric/differential thermal analysis (TGA/DTA), and N2 adsorption-desorption analyses were applied to characterize the as-prepared samples. The total pore volume and average pore diameter of the CuO/ZnO nanostructures were 0.06945 cm3/g and 4.76 nm, respectively. A batch adsorption test was conducted using the as-synthesized samples to evaluate their ability to remove congo red (CR) dye. In the following, the effective parameters in the adsorption of CR by CuO/ZnO nanostructures, including contact time, adsorbent dosage, pH of the solution, initial dye solution concentration, and temperature, were investigated in detail. Also, the kinetic, isotherm, and thermodynamic studies were evaluated. The results indicated that the intra-particle diffusion model (R2 = 0.9990) and pseudo-second-order model (R2 = 0.9998) are suitable models for describing the adsorption rate at the early (0–60 min) and later (60–240 min) times, respectively. According to the Langmuir isotherm model, the maximum adsorption capacity of CR by CuO/ZnO was found to be 357.14 mg/g. Moreover, the negative value for each of the parameters of ΔH° and ΔS° indicates that the adsorption at the solid/solution interface is exothermic and non-random during the process, respectively. Therefore, the proposed eco-friendly and inexpensive green synthesis method can be considered to develop new interesting materials to remove contamination from industrial wastewaters.

Mixed-Linker Strategy for the Construction of Metal-Organic Framework Combined with Dyes toward Alcohol Detection.

Herein, a N-rich metal-organic framework (MOF) with four kinds of cages, Zn4(ade)2(TCA)2(H2O) (NENU-1000, Hade = adenine, H3TCA = 4,4',4″-tricarboxytriphenylamine, NENU = Northeast Normal University), was prepared by the mixed-ligand strategy. Cationic dyes can be selectively absorbed by NENU-1000 at proper concentrations, but not neutral and anionic dyes, which perhaps can be assigned to the N-rich neutral framework of NENU-1000. When NENU-1000 was introduced to a relatively lower concentration of cationic dye solutions (e.g., rhodamine B or basic red 2), the colors of these systems faded quickly. Furthermore, the faded solutions can be used for the detection of methanol and other small alcohol molecules with either the naked eye or common UV-vis spectra. The effect of the length of carbon chain, the position of the -OH group, and the number of the hydroxyl group of the alcohols was explored for the color development rate. In addition, the performance of NENU-1000 in iodine sorption and release was also studied.

Highly efficient removal of dyes from wastewater using nanocellulose from quinoa husk as a carrier for immobilization of laccase

In this study, the synthesis of nanocellulose (NC) from an agro-waste of quinoa husks (QS) was reported for the first time. The NC nano-carrier was utilized for immobilization of a model laccase enzyme (PersiLac1) providing an innovative, green, and practical nano-biocatalyst for efficient removal of two different model dyes (malachite green (MG) and congo red (CR)) from water. This nano-biocatalyst developed a synergistic adsorption-degradation approach leading the dye molecules easily gathered near the nano-carrier by adsorption and then degraded effectively by the enzyme. Upon enzyme immobilization, the dye removals (%) were remarkably improved for both 150 mg/L of dyes (from 54% and 12%, for MG and CR, respectively, in case of the pristine NCs, to 98% and 60% for the immobilized enzyme). The immobilized PersiLac1 could decolorize the concentrated dye solutions and showed superior reusability (up to 83% dye removal after 18th runs for MG) and remarkable performance from complex real textile effluents.

Photodegradation of Methylene Blue (MB) in presence of Strontium Chromate

The textile industries produce wastewater containing toxic synthetic organic compounds like dyes. There were photocatalyst SrCrO4 used for photodegradation of dye Methylene Bluein aqueous media under visible light. The effect of different parameter’s such as Hydrogen ion concentration, concentration of Dye solution, catalyst loading also studied. Degradation has been determined by spectrophotometer at 695nm. A tentative mechanism also has been proposed for the photo catalytic degradation of Dye.

Characterization and Analysis of Argania spinosa Shells from Souss‐Massa Area: Application in the Adsorption of Methylene Blue in Aqueous Solution

This study focused on the adsorption in aqueous solution of methylene blue (MB), a cationic dye used in the textile industry, by crushed Argan shells (used as raw materials) from the southern region of Morocco. These crushed Argan shells were first characterized by different technical analyses: elemental analysis, biochemical analysis, IR spectroscopy, thermogravimetric analysis, scanning electron microscopy, mercury porosimetry, and zetametry. The adsorption kinetics was then studied by varying the experimental parameters such as the dye concentration in solution. We note that at pH = 8, there is an elimination up to 232.6 mg/g, during an equilibrium time of 180 min. The correlation coefficient showed that the pseudosecond‐order kinetic equation best describes the adsorption kinetics for the tested material. The adsorption isotherms of MB by Argan shells are suitably described by the Langmuir model which provide the best theoretical correlation of the experimental data. The thermodynamics of MB adsorption on Argan shells indicates a spontaneous and endothermic process. It was concluded that an increase in temperature leads to a greater adsorption of MB by the studied biosorbent.

First time proficient use of CuS nanoparticles as photcatalyst for degradation of both anionic and cationic dye

In this current manuscript focus is on catalytic efficiency of CuS nanoparticles (NPs). CuS NPs acts as equally outstanding photocatalyst for both cationic and anionic dye. In the process of degradation of both dyes, the catalytic efficiency of CuS NPs is examined by analysing the change in absorption peak of dye by using UV–visible spectrophotometer. The consequence of factors like dopant dose, initial pH of dye solution and initial concentration of dye on photocatalytic efficiency of CuS NPs was explored. CuS NPs demonstrated brilliant degradation of both dyes in presence of UV– visible irradiations. Pseudo-first order kinetics is followed by the degradation process. The velocity constant for both process were productively calculated. Reusability experiments of CuS Nps were conducted to check their utility. Value of rate constant for photocatalysis is high.

Synthesis of chitosan graft poly (acrylic acid-co-2-acrylamide-2-methylpropanesulfonic acid)/graphite oxide composite hydrogel and the study of its adsorption

Chitosan graft poly (acrylic acid-co-2-acrylamide-2-methylpropanesulfonic acid)/graphite oxide (CTS-g-P(AA-co-AMPS)/GO) composite hydrogel is synthesized and used to remove rhodamine 6G (R6G) and methyl violet (MV) from aqueous solutions by adsorption. The composite is characterized by infrared spectroscopy (IR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The effect of the adsorption conditions, including the amount of graphite oxide (GO), the initial concentration of dye solutions, the adsorption time, ionic strength, and the mass of the composite, on the adsorption capacities has been studied in detail. It can be seen that small amount of GO can improve the adsorption capacities of both dyes. It is found that the adsorption capacities of R6G and MV can be increased by 57.26% and 26.39%, respectively, compared with CTS-g-P(AA-co-AMPS graft copolymer. The maximal adsorption capacity of R6G and MV is 625.3 and 326.4 mg/g, respectively. The interaction between GO and dye molecules are speculated. GO acts as crosslinking points and combine with the CTS-g-P(AA-co-AMPS) graft copolymer through hydrogen bonds and electrostatic actions. The adsorption isotherms and thermodynamics are discussed. The Gibbs free energy of R6G and MV is that △GR6GӨ = −2.478 KJ/mol and △GMVӨ = −2.577 KJ/mol and it indicates that the adsorption of R6G and MV on CTS-g-P(AA-co-AMPS)/GO is spontaneous and satisfied the Redlich-Peterson equation. Kinetic studies show that the adsorption is in accordance with the Lagergren pseudo first-order kinetic model.

Removal of organic pollutant from wastewater using Nano Carbon synthesized from wood waste biomaterial as an adsorbent

With the help of eco-friendly waste materials like Manila tamarind tree bark and shells (Pithecellobium Dulce), the malachite green dye has been removed from wastewater in this investigation. The maximum adsorption of dye was achieved at pH 6.7 in the research work. The removal percentage of Malachite green dye was found to be dependent on the initial concentration of dye solution, and the maximum removal percentage was found to be 85% at 25 mg/L of Malachite green dye. The experimental methods were carried out using the batch adsorption technique. The pH parameter, temperature, adsorption dose, and contact time for the removal of Malachite green dye were studied. The Freundlich, Langmuir, and Temkin methods were used to calculate equilibrium adsorption data. The thermodynamic parameters such as a change in free energy (G0 ), enthalpy (H0 ), and entropy (S0 ) were determined. The negative values of G0 indicated that the process of dye removal was spontaneous at all values of temperature. Further, the values of H0 indicated the endothermic nature of the process of dye removal from the wastewater.

Highly efficient visible-light-driven Cu2O@CdSe micromotors adsorbent

Micro/nanomotors have attracted extensive attentions in aquatic environmental remediation, but the random motion and uncontrollability restricts the precise location and timely adjustment in micro-environmental remediation, such as in microchannels and microwells. Herein, we demonstrated visible-light-driven cadmium sulfide quantum dots doped cuprous oxide (Cu2O@CdSe) micromotors adsorbent with excellent removability to cationic dye, in along with effective motion regulation. The Cu2O@CdSe micromotors adsorbent with type II heterostructure was fabricated by simple in-situ deposition and exhibited outstanding motion controllability and instant response under visible light illumination. The existence of a staggered gap between Cu2O and CdSe formed a heterojunction, effectively inhibiting recombination of photogenerated electron-hole pairs and improving photocatalytic activity of Cu2O@CdSe micromotors. Negative phototactic self-propulsion with maximum speed to ∼42.3 μm/s was achieved in biological environments because of the formation of the asymmetric chemical concentration gradient around the motors. Additionally, by modulating the direction and on/off state of asymmetric light field, it is capable of steering motor moving with multiple controllable modes, such as horizontal, vertical, stop/go and patterned propulsion, which will facilitate the on-demand orientation once in the complex microchannel. Furthermore, the capability of Cu2O@CdSe micromotors adsorbent is confirmed with a rapid adsorption rate of 96% on methyl blue after 10 min. Additionally, the stability of micromotors is evaluated. Although with inevitable oxidation or photocorrosion for all Cu2O micromotor, the strong adsorption ability is promised with 5 times recycling in low concentration of dye solution. Such attractive micromachines with boosted motility and lower production cost hold a considerable promise for a complex environmental remediation.

Removal of eriochrome black T from water using a chitosan/zeolite composite: a kinetic study

A composite material was prepared using chitosan and chabazite for the removal of Eriochrome T black dye from water. Scanning electron microscopy (SEM) analyses showed chabazite particles embedded in the chitosan matrix. Thermogravimetric analyses indicated that chitosan degrades chemically at temperatures above 225 °C; chabazite only experiences weight decrease due to moisture loss. Fourier transform infrared spectroscopy (FTIR) analyses on chitosan detected the presence of O-H, N-H, C-H, C-N and C-O bonds, protonated amino groups and saccharides. In chabazite, H2O molecules, T-O and O-T-O groups, where “T” corresponds to Si or Al atoms, isolated H-bonded O-H groups, and Si-O-Si groups were detected. In kinetic experiments, an 86 % decrease of the dye concentration in solution was achieved in approximately 500 minutes. The linearization method was used to evaluate the fit of the experimental data with the pseudo-first-order, pseudo-second order, Elovich and intra-particle diffusion adsorption kinetic models. The kinetic experiments showed that the sorption mechanism corresponds to a pseudo-second order model.

Carbon nanotubes loaded N,S-codoped TiO2: Heterojunction assembly for enhanced integrated adsorptive-photocatalytic performance

A visible-light active N,S-codoped TiO2 incorporated with carbon nanotubes (CNTs) was synthesized by a multicomponent heterojunction scheme. The synthesized photocatalysts was examined by several analysis techniques. The conventional TiO2, N-doped TiO2, TiO2/CNT and N,S-codoped TiO2 were also synthesized, characterized, and integrated adsorptive-photocatalytic degradation rates were subsequently compared and assessed, for comparative purposes as reference photocatalysts. The parametric study was also carried out to investigate the effect of various operational factors, such as solution pH, the photocatalyst loading and initial concentration of dye solution, on the adsorptive-photocatalytic performance. The best activity performance was attained with the N,S-TiO2/CNTs nanocomposite due to the synergistic effect of ternary components caused by the incorporation of dopants and CNTs in TiO2 lattice, providing a high number of adsorption sites and facilitating the effective separation of photogenerated charge carriers and minimal recombination rates. N,S-TiO2/CNTs exhibited around three times higher photocatalytic performance than that of the binary composites, i.e., N-TiO2, TiO2/CNTs, N,S-TiO2, and about four times higher than the conventional TiO2. Furthermore, the superior nanocomposites were also investigated for their recyclability for five consecutive cycles.

Synthesis and characterization of arginine-doped heliotrope leaves with high clean-up capacity for crystal violet dye from aqueous media.

A novel arginine-modified Heliotrope leaf (Arg@HL) was used as adsorbent for the crystal violet (CV) dye adsorption in a batch process. The physicochemical and morphological composition of Arg@HL were characterized by field-emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The experiments were carried out to investigate the factors that influence the dye uptake by the adsorbent, such as the contact time under agitation, adsorbent amount, initial dye concentration, temperature and pH of dye solution. The optimum conditions of adsorption were found on the batch scale as followed: CV concentration of 20 mg·L-1, an amount of 0.75 g·L-1 of the adsorbent, 90 min contact time, 6 pH and 25 °C temperature for Arg@HL. The results confirmed a second-order model explaining the dye crystal violet's adsorption's kinetics by Arg-Heliotrope leaves. The Langmuir model effectively defines the adsorption isotherms. The results revealed that the Arg@HL has the potential to be used as a low-cost adsorbent for the removal of CV dye from aqueous solutions.

Graphene Oxide-Chitosan Aerogels: Synthesis, Characterization, and Use as Adsorbent Material for Water Contaminants.

Porous aerogels, formed by subjecting precursor hydrogels using a freeze-drying process, are certainly one of the most studied and synthetized soft materials, thanks to their important features such as elasticity, swelling behavior, softness, and micro and nanosized pores, which guarantee their applicability in various fields. Typically, these systems are synthetized working with natural or synthetic polymers, but in the last years great interest has been given to proper formulated aerogels able to combine polymeric structures with other moieties such as graphene or graphene oxide. This working strategy can be pivotal in many cases to tune important properties of the final system such as toughness, porosity, elasticity, electrical conductivity, or responsive behavior. In this work we propose the synthesis of chitosan graphene oxide aerogels obtained through self-assembly of graphene oxide sheets and chitosan chains. These three-dimensional systems were chemically characterized with IR and XRD technique and their inner structure was investigated through the scanning electron microscopy (SEM). Moreover, we mechanically characterized the material through dynamic mechanical analysis, showing the stability of these systems. Finally, the adsorption ability of these soft materials has been demonstrated using model molecules to simulate water contaminants showing the efficacy of those graphene-based systems even for the removal of anionic dyes. Complete removal of contaminants was obtained at low concentration of dyes in solution (100 mg/L), while with a higher amount of pollutant in the solution (350 mg/L) high sorption capacity (q > 200 mg/g) was observed.

Photo-degradation, thermodynamic and kinetic study of carcinogenic dyes via zinc oxide/graphene oxide nanocomposites

Pollution problem increases with the same face as the industrial development. One of the toxic ingredients of these industrial effluents is the organic dyes. Zinc oxide/Graphene oxide nanocomposite (ZnO-GNc) was synthesized in aqueous solution by mixing ultrasonically various compositions. The prepared ZnO-GNc nanocomposite was characterized by XRD, FTIR, FE-SEM, EDX and TEM. XRD of Graphene oxide (GO) showed their crystalline nature and the average size was 3.54, 18.98 and 15.47 nm for GO, ZnO, and ZnO-GNc respectively. An active toxic and stable dye, Methyl red (MR) was employed as the target pollutant to evaluate the photocatalytic activity of ZnO-GNc. The photocatalytic performance of ZnO-GNc nanocomposite was compared with that of zinc oxide (ZnO) and GO. The effect of some parameters, dye concentration, pH and temperature of dye solution were studied. The kinetic studies show that the process of MR photocatalytic discoloration by ZnO-GNc followed first-order reaction kinetics under different conditions with the rate constant of 2.2 × 10−2 s−1. The possible reasons for the high values of photocatalytic efficiency of the ZnO-GNc may be due to the improved charge passage and separation.

Controlled Photoanode Properties for Large-Area Efficient and Stable Dye-Sensitized Photovoltaic Modules.

Nowadays, a dye-sensitized solar cell (DSSC) attracts attention to its development widely due to its several advantages, such as simple processes, low costs, and flexibility. In this work, we demonstrate the difference in device structures between small size and large size cells (5 cm × 5 cm, 10 cm × 10 cm and 10 cm × 15 cm). The design of the photoanode and dye-sensitized process plays important roles in affecting the cell efficiency and stability. The effects of the TiO2 electrode, using TiCl4(aq) pretreatment and post-treatment processes, are also discussed, whereas, the open-circuit voltage (Voc), short-circuit current density (Jsc), and module efficiency are successfully improved. Furthermore, the effects on module performances by some factors, such as dye solution concentration, dye soaking temperature, and electrolyte injection method are also investigated. We have demonstrated that the output power of a 5 cm × 5 cm DSSC module increases from 86.2 mW to 93.7 mW, and the module efficiency achieves an outstanding performance of 9.79%. Furthermore, enlarging the DSSC modules to two sizes (10 cm × 10 cm and 10 cm × 15 cm) and comparing the performance with different module designs (C-DSSC and S-DSSC) also provides the specific application of polymer sealing and preparing high-efficiency large-area DSSC modules.

Effects of the silver nanodots on the photocatalytic activity of mixed‐phase TiO2

AbstractWe present the synthesis and photocatalytic properties of mixed‐phase TiO2 nanoparticles decorated with silver nanodots obtained by environmental‐friendly wet chemical method using low molecular weight chitosan as the silver reducing agent. Structural analysis of synthesized Ag nanoparticles revealed that they crystallized in a rare hexagonal modification. High‐resolution transmission electron microscopy study shows that <3‐nm hexagonal‐Ag nanoparticles are implanted on the surface of <20‐nm anatase grains. Compared to Ag‐free TiO2 powders, implantation with Ag results in important increase in visible light absorption. The photocatalytic activity of the samples was measured by monitoring decolorization of concentrated textile dye solution (50 mg L−1 of Reactive Orange 16) under simulated solar irradiation of 280 W m−2. The optimum photocatalytic properties are achieved with 5 wt% of silver. Based on the collected results, the operating mechanism of the degradation process is suggested, and the effects of the silver addition are explained.